<%@ page import="java.util.Enumeration" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%--<%@ page isErrorPage="true" %>--%>
<html>
<head>
    <title>Parameter Names</title>
</head>
<body>
<%
    Enumeration<String> names = request.getParameterNames();
    if(names.hasMoreElements()){
        String name = names.nextElement();
        out.print(name); // 使用 print 方法而非 println
    }
    session.setAttribute("a",null);
    
%>
</body>
</html>